WASHINGTON
— For House Republicans, loyalty to leaders and the mantra of fiscal discipline are articles of faith. But a debate over budget cuts to help offset the cost of rebuilding the Gulf Coast has put those allegiances into open conflict. With the GOP's hierarchy in disarray, the dispute is becoming a fight for the party's soul.

This week will be critical. Facing a revolt from House conservatives, Speaker Dennis Hastert aims to cut at least $50 billion from spending plans for FY 2006, up from $34.7 billion agreed on earlier. But he must do it without the muscle of former House majority leader Tom DeLay, who is now fighting criminal indictments in Texas.

In the Senate, majority leader Bill Frist - facing ethical questions over a sale of stock - is struggling to reconcile conservative freshmen, who are demanding deeper cuts, and powerful committee chairmen, who are rejecting them.

In a rare display of intraparty passions, the fight transformed the staid Senate floor into a rhetorical shooting gallery last week, as freshman Sen. Tom Coburn (R) of Oklahoma took on one of the Senate's most powerful chairmen over the now-infamous "bridge to nowhere."

"We need to wake up.... No more low-priority projects in the face of half-trillion-dollar deficits. No more exorbitant bridges to nowhere," he said, referring to $453 million earmarked for two Alaskan bridges added to the highway bill by that state's senior senator, Ted Stevens. Senator Coburn proposed redirecting those funds to repair bridges in Louisiana destroyed by hurricane Katrina.

In a response laced with shouts, Senator Stevens denounced the Coburn amendment as a threat to state sovereignty. "This amendment is an offense to me.... It is a threat to every person in my state," he said. The amendment failed 15-82.

While embarrassing to Senate Republicans, the floor fight delighted many in the party's fiscal conservative base. "The Coburn amendment was an incredibly important thing. Instead of gentlemen deferring to each other, we saw a humiliating vote on a colleague's efforts to loot the general public," says Grover Norquist, president of Americans for Tax Reform, an anti-tax group.

Until recently, fiscal conservatives dismayed by the pace of spending by the Bush White House and GOP Congress have played down their objections, because Republicans have delivered tax cuts every year of the Bush presidency. But the president's record-low ratings and turmoil in the House leadership is emboldening conservatives and supporters outside Congress to take a higher-profile role.

A defining moment?

"This is a defining moment. The Republican Party came to power in 1995 by advocating limited government. But in the last four to five years, there has been no evidence that the Republican officials in the federal government have any remaining commitment to this vital principle," said Pat Toomey, president of the Club for Growth, at a press briefing with other conservative leaders on Capitol Hill last Thursday.

GOP activists were outraged when Mr. DeLay said, after hurricane Katrina, that there was no more fat in the federal budget left to cut. In response to the fallout from the party's base, DeLay last week appealed to conservative activists at Mr. Norquist's Wednesday morning group to help the party find the 218 votes needed to pass bigger budget cuts.

"They folded back on themselves and decided to become the leader of a parade that could have become a revolt. That is healthy," said Mr. Norquist, after the meeting. If GOP leaders can win agreement this week on a budget reconciliation package, it opens the door for another $70 billion in tax cuts over the next five years.

The stakes are also high for House Democrats. "We can choose to help the people who are affected by Katrina, or we can give tax cuts to the wealthiest people in America," said Democratic leader Nancy Pelosi in a statement before the vote, postponed until this week. She and other Democratic leaders say that not a single Democrat will break ranks to vote for the GOP's proposed cuts.

"If Republicans want to make the case that this is about Katrina, they're going to have to take tax cuts out of the package," says Rep. John Spratt (D) of South Carolina, the ranking Democrat on the House Budget Committee.